Background: Tubal intraepithelial carcinoma (TIC) is a recognized predecessor of metastatic pelvic serous carcinoma and has been studied in earnest since 2005. The majority of reported cases consist of high grade serous intraepithelial carcinomas; however, variants are emerging with the use of more comprehensive protocols for analysis of tubes (SEE-FIM protocol) and study of tubes from women in various risk groups. This study reviewed all TICs coded in a large hospital practice and consultation files between 2005 and 2012, to identify unusual presentations or histologies.Design: The pathology reports from in-house and consultation cases were reviewed for either unexpected presentations of TIC or variant histologies.Results: 150 in-house diagnosie of TIC and 75 consultations for tubal atypias or TICs were reviewed. Three discrete categories were identified. The first was serous TICs found incidentally in women with uterine cancer (7); four were associated with endometrioid adenocarcinomas and three with early serous carcinomas diagnosed by cervical cytology. All four cases associated with endometrioid carcinoma exhibited evidence of altered p53 expression consistent with a separate primary tumor. All four were confined to the fallopian tube at the time of discovery. The second was TICs showing prominent secretory or mucinous differentiation (4). In two there was a coexisting ovarian tumor with the same immunophenotype and strong immunostaining for p53. These also tended to be low stage at the time of discovery. The third was rare early serous carcinomas with apparent altered p53 expression but a very low (less than 10%) proliferative index and a visibly lower grade tumor cell cytology, with focal ciliated differentiation in some cases. All four were discovered incidentally and were not associated with metastases.Conclusions: The three scenarios described from this institutional and consultation experience underscore a potentially wider phenotypic range of tubal intraepithelial carcinomas and suggest that some of these unusual tumor subsets are more likely to be localized. The possibility that a unique subset of women are vulnerable to both endometrial and tubal adenocarcinomas bears further study as does the possibility that rare tumor variants with intermediate (grade 2) histology exist, with a different cell of origin and natural history.Category: Gynecologic & Obstetrics